Foliar Application of Iron Fertilizers to Control Iron Deficiency Chlorosis of Soybean

Core Ideas Iron deficiency chlorosis reduces soybean yield in the Northern Great Plains. Fe‐ortho‐ortho‐EDDHA performed better than other iron forms. Foliar application after iron deficiency chlorosis appearance did not increase yield. Soybean [Glycine max (L.) Merr.] production is significantly reduced by iron (Fe) deficiency chlorosis under calcareous soils of the Northern Great Plains. On‐farm trials were conducted to evaluate the foliar applications of Fe fertilizer forms and addition of different adjuvants according to regreening of leaves and yield. Treated plots had improved visual chlorosis ratings and chlorophyll soil plant analysis development (SPAD) meter readings over the growing season than control, but differences were not significant (P < 0.05). Foliar application of Fe‐EDDHA had the most consistent increase in yield over control of the Fe chelates, but no single adjuvant performed better than the others. Future research should focus on integrating other practices like cultivar selection and high seeding rate with foliar application to control Fe deficiency chlorosis.